318 



Mr. John Allen Harker 



[Feb. i), 



liquid helium under low pressure has succeeded in getting during the 

 last few weeks to within 1 • 1° C. of absolute zero, the highest recorded 

 terrestrial temperature— that of an electric arc under high pressure — 

 falls short of the sun's estimated temperature by some 2000° C. 



Some landmarks in our available range of temperature are given 

 in Table I. It may be remarked that the three substances last quoted 

 in the table are alfin extensive use for electric lamp filaments. 



Table I. — Various Temperatures. 



Table II. gives examples of various flame temperatures 

 we have at our disposal. 



Table II. 



which 



